Digital media data, such as audio and video and still images, are commonly encoded into bitstreams that are transmitted or stored in data files, where the encoded bitstreams conform to established standards. Some examples of such standards are formats derived from ISO/IEC 14496-12 (also called MPEG-4 Part 12 or ISOBMFF) and ISO/IEC 23001-7 (also called CENC).
Standards typically allow some flexibility in a media file format, such that two media files may have different formats yet both still will be compliant with the standard. Such flexibility, however, can mean that compliant file formats are insufficiently constrained. When media file formats are insufficiently constrained, decoders, players and other applications and/or devices can experience errors, performance problems or even security problems.